Many medical procedures in use today require a relatively small sample of blood, in the range of 5-50 μl. Normally such a sample is obtained by lancing or piercing the skin at a selected location, such as the finger, to enable the collection of 1 or 2 drops of blood. With the advent of home use tests such as self monitoring of blood glucose, there is a requirement for a simple and safe procedure which can be performed by a person needing to test.
Lancets in conventional use generally have a rigid body and a sterile pricking element, for example a needle, which protrudes from one end. The lancet may be used to pierce the skin, thereby enabling the collection of a blood sample from the opening created. The blood is transferred to a test device or collection device. Blood is most commonly taken from the fingertips, where the supply is generally excellent. However, blood can also be taken of alternate sites, such as earlobes and limbs.
To reduce the anxiety of piercing the skin and to guarantee a reproducible penetration result many spring loaded lancing devices have been developed.
The lancing device according to the present invention comprises a lancet holder, which is slideable in a housing member between a cocked position and a pricking position. In use the lancet holder carries a lancet which comprises a pricking element protruding there from along an ejection axis. The lancing device further comprises a front cap, which has an opening against which the object to be pricked is to be placed. The pricking element extends through the opening when the lancet is ejected.
Typically the lancet holder is axially slideable along the main axis of a generally tubular housing in forward direction into the pricking position and in backward direction for being loaded.
Conventional lancing devices, as for example disclosed in EP 0 115 388, typically require a user to put a lancet in a socket of a lancing device, arm the lancing device by latching the lancet holder in a retracted position, urge the lancing device against a target site, and then press a release button or other switch to manually activate the lancing device such that a lancet within the device is launched (also referred to as “fired”) towards the target site. The lancet then penetrates the target site, thereby creating an opening for the expression of a bodily fluid sample.
After the lancet pierces the skin, a bounce back spring retracts the lancet to a safe position within the device. Now the lancet can be removed from the lancing device.
Typical lancing devices have a removable front cap, preferably also suited for adjusting the penetration depth. Once the front cap is removed the used lancet can be taken out of a socket of the lancet holder and a new lancet can be put in. When the front cap is removed from the body of the lancing device, the pricking element is exposed and there is a certain risk of injury and of contamination for the person who removes or changes the lancet. Known lancing devices generally are not protected from being fired unintentionally.
Even though many improvements have been made, the handling of the known lancing devices is still complicated for the user and there still is a risk of injury and contamination while replacing used lancets. It is the object of the present invention to overcome the drawbacks of the known devices, in particular to facilitate the change of the lancet, to prevent unintentional lancing and to provide a safe handling, especially of a lancing device with a used lancet.